Eleven to 22% of prematurely born human infants with Respiratory Distress Syndrome (RDS) treated with artificial ventilation and supplemental oxygen therapy, develop a severe chronic lung disease called bronchopulmonary dysplasia (BPD). While many children who had BPD are asymptomatic by three years of age, some can have respiratory symptoms and abnormal pulmonary function tests at nine years of age. The hypothesis to be tested in this study is that abnormalities of pulmonary function seen in infants with BPD can persist into adolescence, even in asymptomatic children and young adults. The specific aims of this research are to (1) measure the cardiopulmonary function in individuals who developed BPD at Stanford University Medical Center (SUMC) from 1964-1974 (N=29) and (2) determine the factors associated with the presence of cardiopulmonary function abnormalities in these children. In addition to the pulmonary function normative data base, two control references will be used: (1) normal individuals from the local community matched for age and sex with the individuals who had BPD. (N=58) (2) Individuals born prematurely at SUMC from 1964 to 1973 who did not have respiratory difficulty at birth (N=29). A detailed interval pulmonary history will be taken. Pulmonary abnormalities will be determined by PA and lateral chest x-ray and pulmonary function tests for small airway obstruction, reversible bronchial hyperreactivity, distribution of ventilation, air trapping and hyperinflation, residual interstitial disease or edema, vascular bed loss, and gas exchange. Right and left ventricular hypertrophy will be evaluated by electrocardiogram. Elevated right ventricular pressure will be estimated by echo-cardiography with doppler ultrasound. The atopic status of the children will be determined. Other abnormalities, including growth retardation, developmental delay, hearing loss, retrolental fibroplasia, and neurologic disability seen in BPD will be assessed by history and physical examination. The information gained from this investigation will be used to determine the need for and the type of cardiopulmonary treatment for children who had BPD (or who were born prematurely) and the need for continued follow-up examination of such infants.